It is often desirable to detect DC currents in circuits or installations. Detection of DC currents is often achieved by the use of a shunt. Shunts have to be inserted in the circuit being monitored and this involves direct contact with the DC supply. In many cases direct contact with the circuit being monitored is undesirable or even impractical. Hall Effect devices are also commonly used for detection of DC currents, but these tend to be bulky and expensive.
Current transformers (CTs) are not normally used to detect DC currents because CTs are only responsive to alternating currents and are not inherently responsive to a steady state current. However, current transformers have the advantage of being compact and inexpensive, and would be an attractive means for achieving contactless detection of DC currents if the above technical problem could be overcome.
It is an object of the invention to provide a simple circuit using a current transformer to detect a DC current.